Multi-aisle warehouse system with mobile lift having control means for an article transfer vehicle

ABSTRACT

A warehouse storage system comprises an array of storage bins arranged in vertical tiers with the tiers arranged in rows and having aisles between the rows. A mobile vertical lift moves across the ends of the aisles and carries thereon a mobile transfer vehicle which can be elevated by the mobile vertical lift to any desired storage level. The self-powered mobile transfer vehicle is adapted to be automatically dispatched from the mobile vertical lift at a predetermined aisle and level and is programmable to travel via tracks along the aisle to a predetermined bin location, and extend retrieving mechanism from the vehicle for transferring the pallet load between the mobile transfer vehicle and the storage bin.

CROSS REFERENCE TO RELATED APPLICATION

This is a division of application Ser. No. 272,287, filed July 17, 1972now U.S. Pat. No. 3,880,299.

BACKGROUND OF THE INVENTION

The present invention relates to a warehouse system and particularly toapparatus for automatically transferring articles to and from thesystem.

With the ever-increasing demands for moving articles, in commerce, ithas become necessary to increase the through-put capacity of warehousingsystems so as to efficiently store and retrieve such articles at thesefacilities which provide retail and other outlets with a variety ofdifferent items. In recent years, the use of semi-automated equipment inplace of manual transferring equipment has been incorporated withlimited success in an attempt to increase the efficiency of warehousingsystems. More recently, stacker cranes have been developed which traveldown aisles of multi-tiered storage bins. These cranes are guided by anoperator who locates the stacker crane across from a desired storagelocation and then either manually picks from that storage location orcan extend lifting forks or the like into the storage bin to store orretrieve articles therefrom. In the more sophisticated systems, theoperator is replaced by some type of electronically operated controlsystem.

Even more recently, a system has been developed that is described inU.S. Pat. No. 3,503,530, Arthur R. Burch, et al., issued Mar. 31, 1970and which employs a first vehicle which travels across the aisles of thestorage rack on tracks and carries with it a second vehicle which can bedispatched down the aisles. The second vehicle includes a mobilevertical elevator for aligning a picking unit with a storage bin. Thepicking unit then can retrieve or discharge articles between the storagebin and the second vehicle. The first vehicle includes a load stationfor transferring the articles between the second vehicle and firstvehicles.

Although such a system represents an improvement in efficiency overmanual picking systems, this system as well as the semi-automaticstacker crane systems lacks the through-put capacity since the vehiclewhich travels in the aisle is adapted to move vertically as well asalong the aisle and therefore, only one vehicle can be employed for eachaisle end. Thus, the maximum numbers of vehicles that actually store andretrieve articles into and out of the system is limited to two for eachmulti-level aisle assuming that each end of the aisle has a firstvehicle that can transfer an associated second vehicle from aisle toaisle. In many warehouses only one aisle end is available therebylimiting vehicles which accomplish the transfer of articles to and fromthe storage bin to one per aisle.

The use of a stacker crane or other systems which have the ability totravel the length of one aisle and elevate within the aisle to any ofthe storage bin heights requires that a single unit have enoughthrough-put capacity to handle the through-put required for each aisle.Because of the input and output systems usually associated at one end ofthe system, it is not feasible to operate two such stacker cranes in oneaisle. This provides, in some cases, a significant limitation to thethrough-put capacity of the system which is best suited for extremelylong aisles of storage. If long aisles are employed, however, thethroughput is limited by the efficiency of the operation of the stackercrane. On the other hand, if the storage location is laid out to includemany short aisles to overcome this limitation, a plurality of therelatively expensive stacker cranes or their equivalent are necessary toobtain the desired through-put. The expense of the system risessignificantly, since each vehicle is relatively complex to providealong-the-asile movement as well as vertical movement in addition to thepicking motion required to reach into a storage bin. Thus, these systemshave undesirable limitations either as to efficiency in their ability toprovide the desired through-put or as to their expense if employed withshorter aisles to provide the desired through-put capacity.

Another important limitation upon existing systems of this type is thefact they require the entire aisle to be unobstructed vertically. Thisis considered a serious fire hazard and places a limit on the height towhich articles may be stored. This invention eliminates this problembecause no or only limited vertical movement of the articles isperformed in the aisles.

SUMMARY OF THE INVENTION

The system of the present invention, however, provides a mobile verticallift that travels across the ends of the aisles in a storage locationand carries a mobile transfer car that can be discharged to any level ofa given aisle by the mobile vertical lift. In this system, thecross-aisle vehicle is vertically movable and can discharge one transfercar at one level of the aisle and second, third, or more transfervehicles at different levels of the same or other aisles. In thissystem, therefore, the number of transfer cars which are used totransfer articles into and out of the storage bins and which can bedispatched along a single aisle is greatly increased. By employingseveral transfer vehicles with a single mobile vertical lift, theefficiency of the warehousing system in its ability to rapidly store andretrieve articles therefrom is greatly increased. Also, since the mobiletransfer vehicles move only in a horizontal plane, they are less complexand, therefore, less costly than vehicles which travel both horizontallyand vertically within the aisles.

It is an object, therefore, of the present invention to provide animproved automatic warehousing system which employs a mobile verticallift that travels across the ends of the aisles in a storage area and isadapted to carry and discharge a second vehicle movable at a singleaisle level along an aisle and which includes means for receiving anddischarging articles from and to a storage bin.

It is another object of the present invention to provide an automaticwarehousing system that employs a single mobile vertical lift and aplurality of mobile transfer vehicles which are adapted to move along anaisle receiving and discharging goods from and to storage bins thereinwhile the mobile transfer vehicle is transporting different mobiletransfer vehicles to other locations within the system.

It is an additional object of the present invention to provide aself-powered mobile transfer vehicle that can be discharged into astorage aisle and transfers goods from and to storage bins and which canleave the system thereby providing an interface between the storage areaand other facilities.

It is an additional object of the present invention to provide a homestation which serves as an interface between the storage system andinput and output conveyors such that mobile transfer vehicles can bedischarged and received by the mobile vertical lift at the home stationfor receiving goods into the system and discharging goods from thesystem thereby.

It is an additional object of the present invention to provide atransfer car storage area where the mobile transfer vehicles can belocated when not in use and are readily available to the mobile verticallift when needed.

It is still an additional object of the present invention to provide aretractable bridge between input and output stations at the home stationsuch that mobile transfer vehicles can be transported between the inputand the output stations when the mobile vertical lift is not at the homestation.

Another object of the present invention is to provide programming meansto automatically control the positions of either the mobile verticallift or mobile transfer vehicle, or both.

A further object of the present invention is to provide locating meanson the mobile vertical lift to accurately align the lift with an aisleand locating means on each mobile transfer vehicle to accurately alignit with a storage bin.

These and other objects of the present invention will become apparentupon examining the drawings together with the accompaning descriptionthereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view in schematic form showing a warehousing systemembodying the materials handling apparatus of the present invention;

FIG. 2 is a side elevational view in schematic form of the warehousingsystem shown in FIG. 1;

FIG. 3 is a fragmentary perspective view of the warehousing systemshowing the detailed structural elements forming the storage racks, theguide rails, the transfer vehicles used in the materials handling systemas well as the home station and retractable bridge employed therewith;

FIGS. 4A and 4B are a detailed enlarged view of the stop elements of thewarehousing system shown in FIG. 3;

FIG. 5 is a side elevational view of the mobile vertical lift shown inschematic form;

FIG. 6 is a detailed sectional view of a portion of the mobile verticallift taken along section lines VI--VI of FIG. 5 showing one of the loadcarrying wheels and associated guide wheels;

FIG. 7 is a detailed front elevational view in cross section taken alongthe section lines VII--VII of FIG. 5 showing the lower drive mechanismfor the mobile vertical lift and its relationship to the tracks;

FIG. 8 is a detailed front elevational view in cross section taken alongthe section lines VIII--VIII of FIG. 5 of the top drive mechanismassociated with the mobile vertical lift;

FIG. 9 is a detailed plan view of the top structure of the mobilevertical lift;

FIG. 10 is a detailed side elevational view of the lifting platformassembly which fits within the mobile vertical lift and is verticallymovable therein;

FIG. 11 is a plan view in schematic form of the mobile vertical lift;

FIG. 12 is a detailed plan view of the aligning means employed with themobile vertical lift;

FIG. 13 is a detailed front elevational view in cross section showing aportion of the horizontal channel members employed in conjunction withthe aligning means shown in FIG. 12;

FIG. 14 is a perspective view of a mobile transfer vehicle;

FIG. 14A is a front elevational view of one of the column labelsemployed to uniquely identify each storage bin;

FIG. 15 is a partial cutaway detailed view of the wheel assemblies inthe mobile transfer vehicle taken along the lines XV--XV shown in FIG.14;

FIG. 16 is a partial plan view of a mobile transfer vehicle;

FIG. 17 is a sectional view partially in cross section taken along thelines XVII--XVII shown in FIG. 16;

FIG. 18 is a side elevational view of a portion of the structure shownin FIG. 17;

FIG. 19 is a plan view in schematic form of a mobile transfer vehicleshowing the location of various sensors thereon;

FIG. 20 is an electrical circuit diagram in block form of a portion ofthe control circuit used with the present invention;

FIG. 21 is an electrical circuit diagram in block form of the controlcircuit for the mobile vertical lift;

FIG. 22 is a diagram in pictorial form of an information transfer panel;

FIG. 23 is an electrical circuit diagram in block form of the controlcircuit for a mobile transfer vehicle;

FIG. 24 is a plan view in schematic form of an alternative embodiment ofthe warehouse of the present invention; and

FIG. 25 is a plan view in schematic form of still another embodiment ofthe warehouse system of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now in detail to FIGS. 1 and 2, there is shown a warehousingsystem comprising a plurality of storage racks 10 separated by aisles 12therebetween which extend along the length of the storage racks 10. Theracks are divided into a plurality of levels and individual storage binswhich form an array of storage locations adapted to receive palletizedloads therein. A transverse aisle 120 extends along one end of theaisles 12 between the two sections of storage racks, and a mobilevertical lift 100 adapted to engage monorails 14 and 16 traverses aisle120. The mobile vertical lift (trans-aisle vehicle) 100 is adapted toreceive any one of a plurality of mobile transfer vehicles 200 which aredispatched into the aisles 12 of the storage system so that materialscan be transferred into and out of the storage bins by the transfervehicles 200.

The mobile vertical lift 100 operates between a home station generallyindicated at 300 which includes input and output stations 320 and 340,respectively, which serves as an interface between the warehousingsystem and other systems such as a receiving station or shippingstation, respectively. The warehousing system further includes atransfer vehicle storage magazine 350 communicant with the outputstation 340 and adapted to store transfer vehicles when not in use. Aretractable bridge 400 facilitates the movement of transfer vehicles 200between the output station 340 across the monorail 16 and the inputstation 320 area when when the mobile vertical lift 100 is not at thehome station. The mobile vertical lift 100 includes a vertically movablelift platform 150 thereon which has a carriage assembly which carriesthe mobile transfer vehicles 200 by means of guide rails 154 adapted toreceive guide wheels on the mobile transfer vehicles 200. The liftplatform 150 is shown in FIG. 2 moving upwardly as indicated by thearrows 152 to an aisle level where a transfer vehicle 200 is in positionto be received by the mobile vertical lift 100. When the mobile verticallift is in position, the guide rails 154 are aligned with horizontalguide rails 18 extending along the aisles 12 of the storage racks 10such that the transfer vehicle 200 can transfer between the mobilevertical lift 100 and aisles 12. The transfer vehicles 200 areself-powered and are guided within the storage racks 10 along the aisles12 by means of the guide rails 18 at a predetermined vertical heightsuch that palletized loads 210 can be automatically transferred betweenstorage locations within the storage racks and the mobile transfervehicles 200 by transfer means carried on the vehicles 200. In FIGS. 1and 2, arrows accompanying the palletized loads 210 and the transfervehicles 200 indicate the direction of movement of the loads into andout of storage and the transfer vehicle motion toward the mobilevertical lift 100.

The mobile vertical lift 100 can be directly coupled to a controlstation 330 (FIG. 1) by means of a festoon cable 325 as shown in FIG. 2to receive positional information from a computer to control themovement of the vertical lift 100 and direct the movement of thetransfer vehicles 200. The cable 325 also provides the mobile verticallift 100 with operating power for its drive motors. The mobile verticallift can also be controlled semi-automatically by employing a punchedcard or like system in which an operator inserts such a card into areader on the lift to control its movement within the system. Likewise,it is possible to manually control the positioning of the lift bycarrying an operator thereon and providing suitable operator controls.

Each mobile transfer vehicle 200 includes its own drive mechanism andpower supply such that it is self-powered in its motion within theaisles 12. The input/output station rails (375 and 358) include anelectrical supply bus or collector bar and each mobile transfer vehicleincludes a contact shoe adapted to slidably engage the collector barsuch that when the transfer vehicle is at the home station area, it canbe externally powered to conserve the electrical energy stored in itsbatteries. It is noted that such a conventional power supply can beemployed at various of the warehouse areas including the access aislesif desired, although in the preferred embodiment, the transfer vehiclesare self-powered when in the aisles. It is seen that by employing asystem such as that shown in FIGS. 1 and 2 whereby the mobile transfervehicles 200 are movable in a horizontal plane and are elevated andlowered by means of a mobile vertical lift at an end of the aisles, thestorage racks can be horizontally divided at predetermined verticalintervals by, for example, fire barriers 30 (FIG. 2) which extendhorizontally through the storage rack area but not through thetransverse aisle 120 in which the mobile vertical lift 100 travels.Thus, when the racks extend, for example, to 100 feet or more in height,they can be divided at several vertical intervals by horizontal firebarriers to lessen fire hazards. It is seen that only the ends of theaisles, and not the storage rack, must be open for the use of thematerials handling equipment of this invention. These open ends can beequipped with fire doors to close them off in case of emergency.

FIGS. 1 and 2 illustrate the use of the materials handling system tointerface with the input and output stations 320 and 340. The inputstation 320 has a conveyor 322 for transferring materials from areceiving station, for example, in a warehousing facility to the inputstation where materials are picked up by a mobile transfer vehicle 200at the input station 320 on guide rails 375. The output station 340 hasa conveyor 345 associated therewith which receives materials from atransfer vehicle 200 at the output station on rails 358 also associatedwith and extending into the vehicle storage magazine 350. Conveyor 345then transfers materials to a shipping dock, for example, that isassociated with the warehousing system. In addition, the facility shownin FIGS. 1 and 2 may include additional input and output means such asthe guide rails 375 which are adapted to guide transfer vehicles 200 toa different facility such as an assembly line within the system. Ashunting or stub conveyor 385 may be located adjacent the rails 375 toreceive preselected loads from some of the transfer vehicles 200 andcarry them to a different area, such as a packaging station. Also,another set of guide rails 395 may be provided at an opposite end of thestorage racks for guiding vehicles 200 to a repair facility, maintenancefacility, or any other of a number of different facilities. Thus, it isseen, by employing a self-powered transfer vehicle 200, the vehicleitself may under its own power and programmed intelligence move betweenthe warehouse facilities shown in FIGS. 1 and 2 to other facilities bymeans of rails 375 and 395 or may transfer loads thereon to variousfacilities as indicated by the associated conveyors 322, 345 and 385.Any number of other variations are possible with such a system thatemploys a self-powered transfer vehicle which includes means thereon fortransferring unitized loads between the vehicle and other means, such asconveyors. The transfer vehicles are, as explained in detail below,programmable to move under their own power to any preselected locationwithin the storage area, or to one of the interface facilities, Havingbriefly described the overall system structure and operation, details ofthe preferred embodiment of the present invention are presented.

Referring now to FIG. 3, there is shown a perspective view of a portionof the warehousing system shown in FIGS. 1 and 2, showing a cutawayportion of a mobile vertical lift 100 and a mobile transfer vehicle 200within an aisle 12 between storage racks 10.

The storage racks 10 comprise vertical supports 20 and load supports 22that define individual storage bins 21 forming an array along eachaisle. The bins 21 are adapted to receive standard palletized loads 210therein as shown. The warehousing system is divided into dual sectionsof arrays of bins 21 that are accessible from adjacent aisles 12. Theguide rails 18 form a portion of the horizontal support members for thestorage racks 10 as well as providing support for the transfer cars 200.As seen in the figure, the carriage assembly 170 on the mobile verticallift 100 also includes guide rails 154 which are adapted to be alignedwith the rails 18 such that a transfer vehicle 200 can be transferredfrom the storage rack 10 onto the lifting platform 150 of the mobiletransfer vehicle 100 on which the carriage assembly rests.

Each transfer vehicle 200 includes a drive motor 250 coupled to guidewheels 270 which ride within the guide rails 18. Additionally, eachtransfer vehicle includes means 230 (FIG. 3) for transferring palletizedloads 210 between a storage bin 21 and the vehicle 200 or between theconveyors 322, 345 and 385 and the vehicle. In the preferred embodiment,means 230 comprise a pair of forks 240 each comprising a three-sectionalplatform having a vertically movable base 232, a middle section 234movable to either side of the vehicle 200, and a top section 236extensible to either side in relation to the middle section 234 andwhich fits under a palletized load 210 for lifting and transferring theload to and from the vehicle 200.

The home station area 300 where the mobile transfer vehicles 200 aretransferred to and from the mobile vertical lift 100, includes aretractable bridge 400 as shown in FIG. 3. The bridge comprises a pairof guide rails 418 mounted above the monorail 16 on which the mobilevertical lift travels and which are lowerable and retractable under theguide rails 375 shown in FIGS. 1 and 3. When the mobile vertical lift100 enters the home station area 300, the tracks 418 are retracted outof the way so as not to obstruct the movement of the mobile verticallift. This is accomplished by mounting the guide rails 418 of the bridge400 on a platform 420 which is mounted to an additional platform 430 bymeans of a pair of actuation cylinders 425. This arrangement allows theplatform 420 to be elevated and lowered in relation to the platform 430.Platform 430 is at approximately ground level and is mounted by means ofguide wheels within a pair of tracks 440 such that it is longitudinallymovable in a direction parallel to the tracks 375 and perpendicular tothe monorail 16.

A motor 445 with a drive belt 450 coupled to the platform 430 can beactuated to cause the platform 430 and, therefore, the platform 425 andrails 418 thereon to be drawn to the left in FIG. 3 out of the way ofthe mobile vertical lift 100, once the rails 418 have been lowered bymeans of the cylinders 425. The bridge 400 is positioned when the mobilevertical lift 100 is not at the home station to provide a transfer pathfor the mobile transfer vehicles 200 from the output station 340 intothe input station 320. The bridge 400 allows the transfer vehicle 200 toreceive a palletized load 210 from the input station 320 or to movealong the tracks 375 to transfer loads to the stub conveyor 385 orotherwise operate between the input and output stations 320 and 340,respectively, without requiring the presence of the mobile vertical lift100. By so designing the system, the transfer cars 200 can be utilizedto their maximum efficiency as can the mobile vertical lift 100.

Both the guide rails 418 of the bridge 400 and the guide rails 154 ofthe carriage assembly 170 associated with the mobile vertical lift 100having locating means 410 and 160, respectively, which are employed inconjunction with tapered ends of the guide rails 18 in the storage racks10 to accurately align the guide rails 154, 418 with the storage rackguide rails 18 such that the transfer vehicles 200 can easily betransferred to and out of the storage rack aisles 12. Details of thelocating mechanism are shown and described with reference to FIGS. 11through 13 and discussed below. The guide rails 18 each include stops 24(only two shown in FIG. 3) at the ends of the rails 18 adjacent theaisle 120 to prevent the transfer cars 200 from accidentally slippingfrom the aisle level when the mobile vertical lift 100 is not inposition to receive the transfer vehicle 200. The construction detailsof the guide rails 18 and stops 24 associated therewith are shown inFIG. 4.

As seen in FIG. 4, the guide rails 18 comprise a longitudinal channelmember 19 having a generally C-shaped cross section. A slightly crownedrail 26 is mounted along the interior bottom surface of the channelmember 19 as shown. Rail 26 carries the weight of the transfer vehicle200 thereon by means of the tapered guide wheels 270 on the transfervehicle which contacts rails 26.

Each of the stops 24 located at the end of each guide rail 18 comprisesa plate 28 having a cross-sectional area sufficiently large to close offthe open area of the guide rail 18. The plate 28 is pivotally coupled tothe C-shaped channel 19 by means of a pivot pin 29. The stops 24 areweighted by means of a weight 31 attached to the plate 28 by means of anarm 33 such that they will normally be held in the position shown insolid lines. In this position, the plate 28 closes off the end of thechannel 19 when the mobile vertical lift 100 is not positioned such thatits guide rails 154 are aligned with the guide rails 18 of the storageracks 10.

The aligning means 160 on the mobile vertical lift, however, are adaptedto swing inwardly when the lift 100 aligns with an aisle and includemembers which contact the stops such that the left and right stops 28are pivoted in a direction indicated by the arrows to the position shownin phantom lines in FIG. 4. In this position, the plates 28 will be outof the way and allow the transfer vehicle 200 to freely move between theguide rails 18 in the storage racks and the guide rails 154 on themobile vertical lift 100. The stops associated with the guide rails 358in the vehicle storage magazine 350 operate in a similar manner to allowthe transfer vehicles 200 to cross the bridge rails or tracks 418 andenter the storage magazine 350 when the locating means 410 havepositioned the tracks in alignment with the guide rails 358 of thevehicle storage area. The construction of the interface between themobile vertical lift guide rails 154 and the guide rails 18 within thestorage racks 10 will be discussed in conjunction with the detaileddescription of the mobile vertical lift 100 which follows.

Referring now in detail to FIGS. 5-13, there is shown a mobile verticallift 100 comprising a base member 102 to which is attached verticalsupport members 104 that extend upwardly from the base member 102 to anupper structure 110 shown in detail in FIG. 9. The mobile vertical lift100 rests on the lower monorail 16 by means of a pair of load supportwheels 103 and 105 coupled to the base 102 by means of brackets 106 and107, respectively. The front portion of the base member 102 is shown indetail in FIG. 6 which illustrates the member 102 as comprising atriangular frame 108 to which is attached the mounting bracket 106 thatholds the front support wheel 103. A pair of support beams 109 extendrearwardly and are coupled to a similar shaped rear triangular framemember (not shown in detail) to complete the frame of the base member102. Rotatably mounted within the frame 108, by means of axles 113 andbrackets 111, is a pair of guide wheels 112 (FIG. 6). These guide wheelsstraddle the lower monorail 16 as shown in detail in the cross-sectionalview of FIG. 7. The rear support wheel 105 also includes a pair of guidewheels and mounting bracket assembly similar to that in the front asshown schematically in FIG. 5 and indicated generally at 114.

The mobile vertical lift 100 is coupled to the upper monorail 14 bymeans of a front pair of guide wheels 115 rotatably mounted to the upperassembly 110 by means of a pair of axles 116 coupled within a frame 117forming the front portion of the upper structure 110 as shown in FIG. 9.It is seen in FIG. 9 that the forward frame section 117 is generallytriangular shaped as is the rear frame member 118 coupled to the frontframe member by means of four strut members 119. A pair of guide wheels122 are rotatably coupled within the rear frame 118 by means of axles124 coupled to the frame 118 by means of a bracket 125.

The lifting platform 150 on the mobile vertical lift 100 is shown indetail in FIG. 10 and comprises a frame assembly 151 having triangularshaped end segments 152 joined by struts 157. The lift platform 150 isvertically movable within the mobile vertical lift 100 by means of aplurality of wheels 155 rotatably mounted to the end segments 152 bymeans of axles 156. Guide wheels 153 are mounted to the ends 152 ofplatform 150 as shown in FIG. 10. These wheels straddle the verticalsupport members 104 of the mobile vertical lift 100 to insure the smoothoperation of the raising and lowering of platforms 150 within the mobilevertical lift 100. The platform 150 also includes a pair of pulleys 158rotatably mounted to brackets 159 on each end 152 of platform 150through which a lifting cable 162 (FIG. 5) is strung such that theplatform 150 can be raised and lowered within the vertical supportmembers 104 of the mobile vertical lift 100.

The lifting cable 162 is also strung through four pulleys 164 mountedbetween the struts 119 of the upper assembly 110 (FIGS. 5 and 9) and isanchored at one end to the structure 110 by anchoring means 165 shown inFIG. 5. The opposite end of cable 162 is attached to a hoisting reel andmotor unit 167 which is selectively actuated as explained below to windor unwind the lifting cable 162 thereon such that the lifting platform150 is raised and lowered.

The mobile vertical lift is driven by means of a drive motor 130 havinga lower axle 132 coupled to a drive gear 134 which engages a rack 17mounted on the side of the lower monorail 16 (FIGS. 5 and 7). The motor130 further includes an upper shaft 136 which is coupled to a drive gear138 (FIGS. 5 and 8) that engages a rack 15 mounted on one side of theupper monorail 14. Shafts 132 and 136 are rotated by the actuation ofmotor 130 in the same direction such that the teeth on the drive gears134 and 138 which engage the teeth on the racks 17 and 15, respectively,causing the mobile vertical lift 100 to travel along the monorails 14and 16.

A carriage assembly 170 is mounted on the lifting platform 150 andcomprises a base member 172 which is attached to the base 152 of theplatform 150 by means of a pivot assembly 175 which permits the carriage170 to pivot a sufficient amount such that the aligning means 160 (FIGS.3, 11 and 12) associated with the guide rails 154 mounted on thecarriage assembly 170 can align the carriage assembly rails with theguide rails 18 within the storage racks 10 (FIG. 3). In someinstallations, the carriage can be mounted to the lifting platform withrollers which permit lateral motion therebetween for aligning thetracks. The operation of the alignment means 160 in conjunction with theguide rails 154 on the carriage assembly 170 is best understood byreferring to FIGS. 11-13.

In FIG. 11, a portion of the mobile vertical lift 100 is shown with theguide rails 154 being illustrated in approximate horizontal alignmentwith the guide rails 18 of the storage racks. Each of the guide rails154 on the carriage assembly 170 has an aligning means 160 at the endadjacent the aisle as shown in the detailed plan view of FIG. 12. Theleft aligning means 160 shown in FIG. 12 comprises a trapezoidal-shaped(as viewed from the top) channel member 180 having a similar crosssection as the C-shaped channel member 19 forming the guide rails 18.The member 180 further includes a short section of rail at the bottom(not shown) similar to rail 26 in FIG. 13. Member 180 is pivotallycoupled to the guide rail 154 by means of a pivot pin 185 and mountingbracket 186. A second bracket 187 is coupled to the member 180 andincludes a roller 188 at the top edge thereof rotatably mounted to thebracket 187 by means of an axle 189. The bracket 187 includes a pivotpin 191 adapted to pivotally hold the end of a shaft 192 of a solenoid195 mounted to the bracket 186.

As the mobile vertical lift is positioned in general alignment with theguide rails 18 of a predetermined aisle level, solenoids 195 areactuated such that both the left and right trapezoidal members 180 (FIG.11) swing inwardly in a manner such that a downward extension of theirleading edge 182 (FIG. 12) will contact the stop plate arm 33 (FIGS. 4and 11) to swing the plate 24 downwardly and out of the way. Thetrapezoidal members 180 come into full contact with the rails 18 therebyjoining the rails 18 with the rails 154 and completing the track overwhich a transfer vehicle can travel between the mobile vertical lift andthe aisle.

To insure accurate alignment, the mobile vertical lift platform 150 isinitially positioned such that the rails 154 are slightly above rails18. As the members 180 are swung inwardly, the rollers 188 will fitwithin the tapered trough 183 formed by the plate 184 which is welded tothe ends of the rails 18 as shown in FIG. 13. Once the solenoids 195 areactuated, the lift platform 150 is lowered somewhat to allow the rollers188 to contact the inner surface 184' of the plate 184, therebypositively forcing the trapezoidal member 180 into aligned engagementwith the rail 18. The laterally movable carriage assembly 170 allows therails 154 and, therefore, members 180 to move such that alignment isachieved.

In this manner, accurate alignment between the rails of the mobilevertical lift and those of the aisles is accomplished. The trapezoidalmember is held in vertical support by means of the flat bottom portion181 (FIGS. 3 and 11) of the guide rails 18 which are not tapered as arethe top portions of the C-shaped channel member 19 forming the rails 18.Thus, as the platform 150 is lowered into position, the rollers 188 inconjunction with the trough 183 assure horizontal alignment of the rails154 with the rails 18 while the protruding bottom portion 181 of thechannel members 19 contact the lower portion of the trapezoidal member180 to assure vertical alignment and support between the rails 154 and18.

Various sensors, limit switches, and other control devices are mountedto the mobile vertical lift 100 and the rack structure 10 as shown inFIGS. 5 and 11 to provide position information as well as variouscontrol functions. The explanation of these devices will be withhelduntil a description of the operation of the system is presented below.Having described the mechanical features of the mobile vertical lift,its horizontal and vertical drive mechanism, and its alignmentmechanism; a detailed description of the transfer car and its structurewill now be presented in conjunction with FIGS. 14 through 18.

The mobile transfer vehicle comprises a frame assembly 220 (FIGS. 16 and17) which is generally rectangular in shape and has rotatably mountedtherein a front axle (not shown) and a rear axle 225. At each end of theaxles is mounted a load support and guide wheel 270. These wheels travelalong the guide rails 18 within the storage aisles, in the guide rails375, 358 on the input and output stations, rails 154 on the mobilevertical lift 100, and rails 418 of bridge 400. As seen in FIGS. 14 and15, an additional horizontally oriented guide wheel 280 is mountedadjacent each of the load carrying wheels 270 by means of a bracket 282coupled to the frame 220 of the mobile transfer vehicle. The additionalguide wheels 280 are rotatably mounted within the bracket 282 by meansof an axle 281 and are located such that as the mobile transfer vehicletravels along the various guide rails, the wheels 280 will just clearthe sides of the guide rails. Since one of these guide wheels 280 isused at each of the four corners of the vehicle, together they insurethat the mobile transfer vehicle will remain relatively stable in thelateral direction as it moves along the rails 18. From time to time theymay contact the inner surface of the guide rails 18 and thereby correctfor any undesirable lateral displacement of the vehicle.

Coupled to the frame 220 of the mobile transfer vehicle 200 is a body205 which may include raised portions 206 and 207 at opposite ends forhousing some of the control and drive units employed with each mobiletransfer vehicle. A removable battery pack 222 for supplying electricalenergy to drive the various electrical motors is mounted at one end ofthe housing 207. The load transfer means 230 for transferring palletizedloads comprises a pair of forks 240 each having base, middle and topsections 232, 234, and 236, respectively. The forks 240 can besimultaneously or individually raised and extended to either side of thetransfer vehicle as described in detail below. Each of the forks 240 aremounted to a platform 245 which can be raised and lowered therebyelevating or lowering the forks 240.

Each of the mobile transfer vehicles 200 may include locating means 290(FIGS. 14 and 16) comprising a forked element 295 coupled to a shaft 297driven by actuation means 298. The operation of the locating means 290,if employed, is explained in greater detail with reference to FIG. 16below.

Each of the mobile transfer cars also includes sensing means 265 mountedon the end segment 206 of the body 205 to detect bin positions andidentification indicia thereon by optical detection means. Sensors 265include a light source 266 and a plurality of photoelectric detectors267. In addition to the bin detecting sensor 265, each of the mobiletransfer vehicles 200 includes information transferring means 650 (FIGS.19 and 22) which interfaces with mobile vertical lift informationtransferring means as described below such that the mobile transfer carcan be programmed from the mobile vertical lift and transfer diagnosticinformation to the lift when the mobile transfer vehicle 200 is inposition on the lift 100.

Referring now to the detailed FIG. 15, there is shown a cutaway view ofone of the vertical support members 20 which make up the storage racks10 shown in FIGS. 1-3. Coupled to the vertical support member 20 is ahorizontal bin support 22. Each bin comprises at least two supportsspaced to receive a standard palletized load thereupon. Bolted to thesupports 20 and 22 by means of bolts 27 is a Z-shaped bracket 25 whichsupports both the horizontal bin support 22 and aids in supporting thechannel member 19 of guide rails 18. It is seen in FIG. 15 that theguide rail 18 is positioned somewhat below the horizontal bin support 22such that the forks 240 (FIG. 14) are vertically positioned to allowthem to slide under a palletized load when removing a pallet from astorage bin 21 as shown in FIG. 3.

The rail 26 which is welded to the bottom surface of the C-shapedchannel member 19 forming the guide rails 18, is crowned somewhat asshown in FIG. 15 and each of the wheels 270 on the transfer vehicles 200is tapered slightly as shown in FIG. 15 such that the transfer vehiclewill be self-centering on the crowned rails 26. As noted above, theadditional guide wheels 280 aid in stabilizing the transfer vehicles ina lateral direction in the event some lateral displacement occurs.

Although the preferred embodiment described employs a transfer vehicle200 adapted to follow guide rails 18 within each aisle, in otherembodiments, the transfer vehicle could be supported by horizontalfloors between each storage level such as the horizontal fire barriers30 shown in FIG. 2. In such an arrangement, the front edges of thestorage bins would guide the vehicles along the aisle while the floorwould provide support and vertical registration between the vehicles andthe storage bins.

Referring now in detail to FIGS. 16, 17 and 18, the structure andmechanical operation of the forks 240 and drive mechanism for a transfervehicle 200 is presented.

As shown in FIG. 16, the drive motor 275 which is used to propel thetransfer vehicle 200 along the various guide rails is coupled to therear axle 225 of the transfer vehicle by means of a cog belt 276 coupledto a cog pulley 279 mounted on an axle 277 of the drive motor 275. Abearing block assembly 278 supports the shaft 277 on which the cogpulley 279 is mounted. A similar cog pulley 274 is mounted to axle 225such that the rear axle 225 is positively engaged and driven by the cogbelt 276 joining pulleys 274 and 279. The rear axle 225 is supported ateither end by bearing block assemblies 226 and 227 as shown in FIG. 16.The drive motor 275 is a reversible direct current motor that receivesenergy from the rechargeable battery pack 222 (FIG. 14) mounted on thetransfer vehicle. The motor 275 is controlled as described below todrive the transfer vehicles along the various guide rails of the system.In some systems where self-powered vehicles are not employed, variablespeed A.C. motors can be used on the transfer vehicle and receive theiroperating power from a collector bar along the tracks and the slidingcontact shoe on the transfer vehicle in much the same manner as thevehicle of the preferred embodiment receives D.C. power while at theinput/output stations.

The locating means 290 which may be employed with the transfer vehicle200 comprises a fork member 295 having a pair of rollers 292 at the endof each of the tines of the fork. The fork 295 extends from the side ofthe transfer vehicle at a position such that when it is retracted asshown in solid lines in FIG. 16, the rollers 292 clear the verticalsupport members 20 of the rack 10 so as not to interfere with the motionof the transfer vehicle. As the transfer vehicle stops in generalalignment with one of the storage bins of the rack 10, the electricallyoperated actuation means 298 can be selectively controlled as describedbelow to cause the shaft 297 to which the fork 295 is attached to extendoutwardly to a position shown in dotted lines in FIG. 16 such that thetines of the fork member 295 straddle the vertical member 20 and causethe transfer car 200 to move slightly (if necessary) so that it isaccurately aligned with the storage bin. This horizontal alignmentfacilitates the operation of the load transferring forks 240 which mustfit under the pallet such that the palletized load can be transferred toand from the storage bin. It has been discovered that with the binlabels 11 (FIGS. 3 and 14A) which are detected by the transfer vehiclesensors 265 (FIG. 14) and the control for the transfer vehicle drive,sufficiently accurate positioning of the vehicle in alignment with thestorage bins can be obtained and the locaters are unnecessary. In lesscomplex vehicle drive control systems which, for example, employ onlybin counting, the locaters are used and their operation will bediscussed below.

The forks 240 are mounted on a platform 245 which is raised and loweredby means of a pair of raising motors 242 which drive threaded shafts 244located at each corner of the platform 245 and coupled to the raisingmotors by means of gear boxes 243 (FIG. 17). FIGS. 16 and 17 show thedetails of the raising mechanism at one end of the platform 245 whileFIG. 19 schematically shows both raising motors 242. The motors 242 arereversible direct current drive motors which receive power from thebattery pack 222 on the mobile transfer vehicle and are simultaneouslycontrolled as described below. The platform 245 is threadably mounted toeach threaded shaft 244 by means of a bracket assembly 245' having apair of vertically spaced threaded nuts 246 such that as the four shafts244 rotate, the platform 245 will be raised or lowered. Supporting therotating shafts 244 at either end are bearing block assemblies 248. Apair of sprockets 249 coupled to the shafts 244 and joined by a chain249' drive each pair of shafts 244 at one end of platform 245 with asingle raising motor 242. In some embodiments, platform 245 may be splitinto two sections and the raising mechanism designed to allowindependent raising and lowering of each form 240 thereon.

The base member 232 of each fork 240 is rigidly secured to the platform245 and is vertically movable therewith. The base 232 has a pair ofvertical walls 233 with longitudinally extending channels 231 alongtheir inner surface (FIG. 17). The base 232 also includes an openchannel 231' in the bottom which extends the length of member 232 andallows the extension mechanism, which mechanically joins the middle andtop sections 234 and 236 to the extension motor 212, to passtherethrough. The extension motor 212 is mounted to the platform 245 andis coupled to a drive gear 215 on shaft 211 by means of a pair ofsprockets 213 between which is coupled a drive chain 213'. A clutch 211'is interposed in shaft 211 to permit one or both of the forks to beextended. The motor 212 is a direct current reversible motor driven bythe same battery source as the remaining motors and controlled asdescribed below.

A second or middle section 234 of each fork 240 is shown in detail inFIG. 18 and includes rack 214 along the bottom which has teeth adaptedto engage the drive gear 215. The second section 234 is slidably mountedwithin the channels 231 in each of the vertical walls 233 of the basemember 232. The sliding contact between the middle and base sections isaccomplished by means of a plurality of rollers 216 which are rotatablymounted to the vertical walls 235 of the middle section 234, by means ofaxles 217. Also mounted on the outer edge of each of the vertical walls235 of the middle section 234 are a pair of nylon guide plates 218 asshown in FIG. 18. These serve to provide additional support and preventtilting of the second section 234 with respect to the base section 232when the fork 240 is outwardly extended with a load thereon. As seen inFIG. 18, each end of the middle section 234 has a pair of guide rollers216 and a guide plate 218 at each end of each side of the middlesection.

As shown in FIG. 17, (which illustrates one of the two identical forks240) the inner side of the vertical walls 235 of middle section 234 alsoincludes a plurality of guide rollers 219 which are also coupled toaxles 217 and are aligned with the rollers 216 on the opposite side ofthe vertical walls 235 of the middle section 234. These rollers extendinto longitudinal channels 237 in the vertical walls 238 of the topsection 236 of the fork 240. Nylon guides (not shown) are also mountedbetween the rollers 219 in a similar manner to the plates 218 shown inFIG. 18 but on the opposite side of the vertical walls 235 of middlesection 234. Thus, the top section 236 can slide relative to the middlesection 234 and be held in a stable position by means of the rollers216, 219 and guide plates 218. The mechanism for extending the middleand top sections 234 and 236, respectively, by means of the extensionmotor is now discussed.

As noted above, the shaft of the extension motor is coupled to the gear215. This gear positively engages the rack 214 on the middle section 234such that the middle section can be extended from either side of vehicle200 to reach a storage bin 21 on either side of an aisle. A pair ofchains 239 longitudinally span the middle section 234 (FIG. 18) and areheld in aligned slidable engagement to the middle section 234 by meansof the guides 241 which are integrally formed with a center block 242secured to the middle section 234 (FIG. 17). The bottom section 232includes a pair of racks 243 which have upwardly directed teeth adaptedto engage the individual links of the chains 239 such that the bottomportion of the chain will engage the racks 243 of the base section 232as the middle section 234 is extended by means of the rack 214 androtating gear 215. As the middle section travels outwardly, however, thechain is allowed to rotate longitudinally around the guides 241 of thecenter section and a pair of racks 243' mounted to the top section 236having downwardly directed teeth adapted to engage the individual linksof the chain 239, cause the rotating chain to extend the top section 236outwardly relative to the middle section 234. Thus, as the extensionmotor 212 drives the gear 215, the middle section 236 is drivenoutwardly and at the same time, the top section is driven outwardly at agreater rate relative to the base by means of the pair of rotatingchains 239 mounted to the middle section 234 by the links that engagethe racks 243' in the top section 236.

Both forks 240 are driven by axle 211 coupled to extension motor 212(FIGS. 16 and 19) and a pair of gears 215 which are joined by means ofan additional chain 247 which engages sprockets 247' that are coupled tothe drive gears 215. In this manner of coupling therefore, one extensionmotor 212 is employed to extend each of the forks 240 to the left or tothe right side of the transfer vehicle 200. Clutch 211' permits theextension of only one fork which is desirable when half sized palletloads are stored in the bins and only one fork is required to removethem. In some embodiments, it may be desirable to independently operatethe forks. In such case, a pair of extension motors 212 (the secondmotor shown in phantom in FIG. 19) are coupled to drive gears on theforks which then can be independently operated in either direction. Inthis arrangement, clutch 211' is eliminated.

Thus, it is seen by the mechanism shown in FIG. 16 through 19, each fork240 is vertically movable and extendible to either side of the transfervehicle such that a load can be lifted by the vehicle, extended into astorage bin, and then lowered until the pallet contacts the horizontalbin supports 22 (FIG. 15). The forks are then retracted onto thetransfer vehicle leaving the pallet load in the bin. Likewise, the forkscan be extended first under the pallet load in the bin, raised to liftthe pallet load from the storage bin supports and retracted to bring thepallet back to the transfer vehicle. In this manner, palletized loadsare transferred between the mobile transfer vehicle and the storage binsas well as the input-output conveyors and other interface equipment. Theforks are described in greater detail in a co-pending applicationentitled "MOBILE TRANSFER VEHICLE AND LOAD TRANSFERRING MEANS THEREFOR",assigned to the present assignee and filed concurrently herewith.

Having described the mechanical design and physical operation of thevarious parts of the mobile vertical lift, the mobile transfer vehicleand the storage racks; a description of the operation of the system tostore and retrieve palletized loads is now presented. First, adiscussion of the store or input mode of operation in conjunction withthe various sensors on the vehicles and at various other locations inthe system is presented. Reference is had to FIGS. 1, 3, 5, 11, and19-23, which schematically show the location of the vehicle sensors andassociated means which operate the sensors mounted on the storage racks.

For the purpose of initiating the description of the devices operation,it is assumed that the mobile vertical lift 100 is not at the homestation 300 but is somewhere along the aisle 120 as shown in FIG. 1. Itis also assumed that a palletized load 210 is entering the input station320 by means of the conveyor 322. It is desired to store the incomingload 210 in a predetermined storage bin. The first step in the storagemode of operation is to position a mobile transfer vehicle on the rails375 at the input station 320 such that the forks 240 on the mobiletransfer vehicle 200 can transfer the palletized load 210 from the inputstation 320 to the mobile transfer vehicle.

Referring now to FIG. 20, which is a combined logic flow diagram andelectrical control circuit diagram, the first operation necessary in thestore mode of operation of the system is to position the transfer car atthe home station 320. A sensor S-1 (FIG. 1) which may be an opticalsensor is located at the end of input conveyor 322 so as to provide asignal indicating the presence or absence of a palletized load 210thereon. Sensor S-1 is coupled to a first logic circuit 500. A secondsensor S-2 (FIG. 1) is likewise coupled to the logic circuit 500 and isphysically located adjacent the tracks 375 at input station 320 anddetects the presence or absence of a transfer car 200 at the inputstation. The sensor S-2 provides an output signal indicative of thisinformation which is also applied to circuit 500. If a palletized loadis present at the end of conveyor 322 and, if the signal from S-2indicates that a T-Car is not present at the input station 320, thelogic circuit 500 will provide a control signal which is employed toactuate the retractable bridge 400 such that a transfer vehicle 200 canbe brought across the bridge from the storage magazine 350.

A bridge control circuit 502 (FIG. 20) receives an actuation signal fromthe logic circuit 500 and simultaneously receives a signal from a sensorS-3 (FIG. 1) which is an optical sensor placed adjacent the bridge areaand provides a signal indicating the presence or absence of the mobilevertical lift 100 at the home station 300. If the mobile vertical lift100 is not in the way of the bridge 400, the bridge control circuit 502will provide an electrical actuation signal which is applied to a motorcontrol circuit 504 which actuates the bridge motor 445 (FIG. 3) toextend the retractable bridge 400 outwardly across the monorail 16.After the bridge is extended, the motor control circuit develops asignal applied to circuit 506 to actuate the lifting cylinders 425 suchthat the guide rails 418 associated with the bridge 400 will be elevatedand vertically aligned with the guide rails 375 of the input station andthe guide rails 358 of the magazine 350.

Once the guide rails 418 are in position, circuit 506 develops a signalwhich is applied to circuit 508 to actuate the locators 410 at the endof each guide rail 418 such that they swing into place to securely lockthe bridge guide rails 418 to the guide rails 358. Once the locators 410are positioned, a sensor S-4, (FIG. 3) which may be a limit switch thatdetects the locked-in position of the locators 410, provides an enablingsignal which permits an operator at station 330, or if fully automaticoperation is employed, the computer to actuate the first one of themobile transfer vehicles 200 in the storage magazine 350 or at theoutput station 340 (FIG. 1) to cross the bridge. This is accomplished bycoupling the output of sensor S-4 and a command signal from a pushbutton switch 512 or the computer to a mobile transfer vehicle controlunit 510 which is coupled to an array of optical informationtransmitting means 370 (FIG. 1) located adjacent the output station 340of the transfer vehicle magazine 350. Light sources in an array on theunit 370 are in a position to actuate optical sensing means 650 (FIG.19) mounted on the mobile transfer vehicle 200. The optical interfacebetween the transfer vehicle 200 and the storage magazine 350 isidentical to that of the transfer vehicle and the mobile vertical lift100 and will be described in detail below with reference to theoperation of the mobile transfer vehicle and in conjunction with themobile vertical lift. It is sufficient for the understanding of theoperation of the storage magazine, however, to note that the circuit 510will actuate the drive motor of the mobile transfer vehicle in thestorage magazine 350 causing the vehicle to move in the proper directionacross the bridge tracks 400 and to the input station 320 on rails 375.At the same time, another transfer vehicle (if any) in the magazine 350is automatically advanced to the output station 340. This can beaccomplished by a gravity feed arrangement by mounting tracks 358 on anangle and providing a retractable stop at the output station, or byother means.

Once the mobile transfer vehicle 200 is at the input station, sensor S-2detects the vehicle and applies a signal to the logic circuit 500 whichresponds thereto to apply a signal to circuits 502 and 508 to retractthe bridge 400 out of the way such that the mobile vertical lift 100 canbe brought to the home station 300 and receive the transfer vehicle 200.Simultaneously, while the bridge 400 is being retracted, the mobiletransfer vehicle 200 is programmed at the input station 320 by theoptical interface to automatically extend the forks 240 by the mechanismdescribed above in conjunction with FIGS. 16-18 to fit under thepalletized load 210 at the end of the input conveyor, lift the load,retract the forks to the transfer vehicle 200. After the bridge 400 hasbeen retracted, the mobile vertical lift is controlled to return to thehome station 300 either by the operator or automatically by thecomputer.

The palletized load 210 will include an information card as to thenature of the load, its quantity, and possibly the storage bin location.In a semi-automatic operation, the operator will read the informationand choose the storage location and address and type it into thecomputer control circuit 530 by means of a data keyboard 525 (FIG. 20),at the operating station 330. In a fully automatic system, thisinformation is punched into a computer data card accompanying the load210. The operating station 330 includes a data card reader 520 whichreceives the punched computer card and from the identification of thetype of goods and the quantity, will transmit data signals to a computerin a computer control circuit 530. A memory core in circuit 530 providesa continuous inventory of goods presently in the storage racks 10 andtheir particular location. With the information from a data card 522(FIG. 20) associated with each incoming pallet load 210, the computercontrol circuit 530 develops a signal which is applied to the mobilevertical lift control unit 610 on the mobile vertical lift via festooncable 325 (FIG. 2). The signal includes information employed to programthe mobile transfer vehicle 200 to move onto the mobile vertical lift100 at the home station 300. The signal also includes informationprogramming the travel of the mobile vertical lift to the desired aisleand aisle level for dispatching the mobile transfer vehicle.Simultaneously, the receipt of the articles comprising load 210 isentered into the memory to update the inventory information.

The signal applied to the mobile vertical lift control unit 610 from thecomputer control circuit 530 can take the form of a binary coded decimalsignal, a stream of data bits, or other formats depending upon theparticular design choice. Before describing the movement of the mobilevertical lift and the mobile transfer vehicle in the store mode ofoperation of the system, it is important to note that the systemalthough particularly well adapted to be automatically operated asdescribed thus far can be semi-automatically operated by an operator byemploying a data keyboard 525 which is coupled to the computer controlcircuit 530. For example, as a load enters the input area, the operatorcan visually check the position of the mobile vertical lift, thetransfer vehicles, and the retractable bridge from his operating stationand type an appropriate data control signal into the computer controlcircuit 530 by means of the keyboard 525 to control the position of thevehicles and the bridge. The computer control circuit 530 is coupled tothe logic circuit 500 and to the mobile transfer vehicle control circuit510 at the output station 340 such that the operator can control thebridge and mobile transfer vehicles in the storage magazine from theoperating console. He also can control the position of the mobilevertical lift in a similar manner.

Referring now to FIG. 21, it is seen that once the mobile vertical lift100 has returned to the home station under the command of the computercontrol circuit 530, and the mobile transfer vehicle has been loaded andis at the input station 320 (FIG. 1) adjacent the home station; thesensor S-3 detects the presence of the mobile vertical lift 100 andprovides a control signal to the mobile transfer vehicle control unit510' which is associated with the input station 320 and which includesan optical interface 370 (FIG. 1) which aligns with the informationpanel 650 included in the transfer vehicle control circuit 600 locatedon each mobile transfer vehicle 200. The optical coupling between units510' and 600 is indicated by the dashed lines in FIG. 21 between theunits.

The panel 650 on each of the mobile transfer vehicles 200 can be mountedon the sides or bottom of the vehicle (FIG. 19) and the units 370 aremounted adjacent or under the guide rails such that when the vehicle 200is at the input or output station or other locations; the units will bealigned so information can be exchanged therebetween. It is noted herethat the lifting platform 150 on the mobile vertical lift is loweredwhen the lift is at the home position such that the guide rails 154 onthe carriage assembly 170 are aligned with the guide rails 375 once thesensor S-3 detects the presence of the mobile vertical lift. Thecarriage assembly 170 (FIG. 11) is, therefore, in position to receivethe mobile transfer vehicle 200. The aligning wedges at the end of rails154 (not shown) accurately couple rails 154 to rails 375.

Having received the signal from the S-3 sensor, the circuit 510'actuates the mobile transfer vehicle which moves onto the mobilevertical lift. The mobile transfer vehicle automatically senses itsposition on the mobile vertical lift as discussed below and whenproperly positioned, the drive motor for the mobile transfer vehicle isdeactivated with the vehicle 200 resting upon the mobile vertical lift100. The locating means 290 (FIG. 14) on the mobile transfer vehicle 200can be extended to engage a frame member on the lifting platform 150(FIG. 10) such that the mobile transfer vehicle is locked into themobile vertical lift 100. The control and positioning of the mobiletransfer vehicle onto the mobile vertical lift is described in greaterdetail when the description of the operation of a mobile transfervehicle within an aisle is presented, the operations being substantiallyidentical.

The control and interface circuit 610 is located on the mobile lift 100such that once the mobile transfer vehicle 200 is properly positioned onthe lift, the information panel associated with the circuit 610 and theinformation panel 650 of the mobile transfer vehicle control circuit 600(FIGS. 11 and 19, respectively) will be physically aligned such that theoptical information transfer means can effectively communicateinformation between the two vehicles by means of light sources andsensors contained therein as described below.

The mobile vertical lift control circuit 610 is coupled to the computercontrol circuit 530 as shown in FIG. 20. Once the mobile transfervehicle is properly positioned on the carriage assembly 170 and,therefore, on platform 150, a limit switch L-1 (FIG. 11) on the lift 100is contacted by a cam member C-1 (FIG. 19) on the mobile transfervehicle 200 to actuate the switch. Switch L-1 is electrically coupled tothe mobile vertical lift control circuit 610 to provide a signal to thecontrol circuit indicating that the mobile transfer vehicle 200 isproperly positioned and the mobile vertical lift can proceed alongtransverse aisle 120 (FIG. 1) to the pre-programmed aisle and elevatethe transfer vehicle to the desired level. The motion of the mobilevertical lift is programmed by, for example, storing a predeterminedcount from the computer that corresponds to the desired aisle and binlevel in a storage counter. The digital count in the storage counter isalso applied to a digital comparator which compares the count on thisinput with the count from a reversible counter whose count varies withthe movement and actual position of the lift 100 by employing sensorswhich detect the position of the lift 100. As the mobile vertical lift100 travels along aisle 120, the counter is decremented or incrementedas the mobile vertical lift sensors detect each aisle and level asexplained below until the counts compared by the comparator areidentical. At this time, the comparator provides a control signal tostop the motion of the mobile vertical lift. A similar arrangement canbe employed to control and to determine the vertical position of thelift platform 150. Thus, a pair of digital comparators, storage andreversible counters together with the conventional control circuits canbe employed to cause the mobile vertical lift to move along aisle 120 aswell as to elevate lifting platform 150.

Referring now to FIGS. 5 and 11, 21, 22 and 23; the sensors to determinethe vertical and horizontal position of the mobile vertical lift whichare on the mobile vertical lift as well as mounted to the storage rackson the end adjacent the aisles 120 will be discussed in conjunction withthe associated control circuits.

First, the controlled horizontal motion of the mobile vertical lift downan aisle is discussed. As shown in FIG. 11, there are four limitswitches L-2 through L-5 which are mounted to the lift 100 and areassociated with cams C-2 through C-5, respectively, which canconveniently be mounted in a vertically spaced array to the horizontalsupport rails 22 (FIG. 3) or extension thereof at the end of the storagebins 10 adjacent aisle 120. These cams can be raised members of variouslengths to selectively actuate associated limit switches as the mobilevertical lift travels along the monorails 14 and 16. The limit switchesare electrically coupled to the control circuits as shown in FIG. 21 toprovide position information to the circuits. For simplicity, adiscussion of the control circuits will be limited to a three-aislesystem, it being understood that additional aisles will be actuallyemployed in a warehouse system and several additional limit switcheswill be employed to uniquely identify each aisle.

The first two limit switches L-2 and L-3 are adapted to be actuated bythe cams C-2 and C-3 to provide a signal indicating alignment of thelift 100 with any one of three possible aisles. For a system servicing agreater number of aisles, additional cams can be added. As the mobiletransfer vehicle is propelled down the aisle 120 by means of theactuation of drive motor 130 by the mobile vertical lift control circuit610, the limit switches L-2 and L-3 will be actuated by the presence orabsence of corresponding cam members forming C-2 and C-3. As theactuation of these two limit switches occurs, the count feed to areversible counter 615 from circuits 610 (FIG. 21) changes to correspondto the digital count assigned to identify the aisle corresponding to theposition of the mobile vertical lift 100 before it reaches the desiredaisle. It is noted here that in a fully automatic system, the countersand comparators can be incorporated into the computer control. It isalso noted here that any desired signalling system can be employed tocontrol the motion of the mobile vertical lift to the desired aisle.Magnetic, optical or other sensing systems could be employed in place ofthe mechanical system described herein.

Once the mobile vertical lift has passed the aisle prior to the desiredaisle, the limit switches will be actuated to provide a count to thedigital comparator 617 which corresponds to the preset count feed to thedigital comparator from the computer circuit 530 via storage counter619. As this occurs, the digital comparator develops a control signalapplied to a drive or travel motor control circuit 613 whichsimultaneously actuates the circuits associated with the limit switchesL-4 and L-5. Cam C-4 is positioned to actuate limit switch L-4, as thelift 100 approaches the desired aisle. With L-4 actuated, the drivemotor 130 slows down thereby decreasing the speed of the mobile verticallift 100. As the mobile vertical lift comes into general alignment withthe guide rails 18 of the desired aisle, cam C-5 is positioned toactuate the limit switch L-5 which provides a stop signal to the motor130 thereby deactuating the motor and causing the mobile vertical liftto stop in approximate alignment with the desired aisle. Criticalalignment is unnecessary due to the design of the platform 150 with thecarriage assembly 170 and aligning means 160 thereon described below. Inthis manner, therefore, the mobile vertical lift can be programmed totravel to a desired aisle. Once the transfer car has been dischargedtherefrom, the mobile vertical lift can receive a command from thecomputer 530 to return to the home station 300 or any other position.The command changes the count on the storage counter 619 to correspondto the desired aisle location or home position and the mobile verticallift is actuated to travel to the new position. In some cases, themobile vertical lift 100 will not be needed elsewhere and can await thereturn of the mobile transfer vehicle. Having described the horizontalmotion of the mobile vertical lift along aisle 120, a description of theoperation of the lift platform 150 on the lift 100 is presented.

The computer control circuit 530 shown in FIG. 20 also programs themobile vertical lift control unit 610 with information as to the aislelevel at which the transfer car thereon is to be discharged. This isaccomplished by a second storage counter 620 which receives apredetermined count from computer control circuit 530 corresponding tothe desired aisle level. The count so stored in counter 620 is coupledto one input of the digital comparator 625 which receives a second countinput from a reversible counter 630 whose count is controlled by thelimit switches L-6, L-7 and L-8 shown in FIG. 5. These limit switchesare mounted to the lift platform 150. Cams C-6, C-7 and C-8 are mountedto the vertical support member 104 of the mobile vertical lift 100 andare positioned at levels corresponding to the desired aisle heights in aplurality of groups of cams C-6 through C-8 mounted to the verticalsupport member 104 as shown schematically in FIG. 5. Each of the limitswitches L-6 through L-8 can be weighted as, for example, by 1, 2 and 4bit weighting such that a digital code is formed thereby which uniquelyidentifies up to seven aisle levels, it being understood that toincrease the number of aisle levels, it is only necessary to increasethe number of limit switches and associated cams. The limit switches areelectrically coupled to the circuit 610 to provide a count uniquelyidentifying each aisle level as the lifting platform 150 approaches theaisle level.

The hoist motor 167 (FIG. 5) is actuated by the circuit 610 via a motorcontrol circuit 627 as the mobile vertical lift 100 leaves the homestation 300. As the lift passes the aisle level just prior to thedesired aisle, the digital comparator 625 senses coincidence of countsfrom the storage counter 620 and the reversible counter 630 to provide acontrol signal to energize limit switches L-9 and L-10 shown mounted onthe platform 150 on the right side of FIG. 5 which operate to stop andslow down the vertical travel of the lift platform 150 in the samemanner as limit switches L-4 and L-5 slow down and stop the horizontalmotion of the mobile vertical lift 100. Thus, cams C-10 and C-9 aremounted on the mobile vertical lift support member 104 in groups asindicated schematically in FIG. 5 and are positioned to contact theassociated limit switches L-9 and L-10 to slow down and stop the liftplatform 150 as it reaches the desired aisle level.

The hoist and travel motors 167 and 130 respectively, receive initialactuation control signals from circuit 610 via their respective controlcircuits. In some installations, the speed of the motors can be variedinversely as the difference between the counts in the storage andreversible counters. Thus, if the lift has a long way to travel, thespeed of the drive motor is initially fast and can be continuously orincrementally slowed as it approaches the desired aisle as evidenced bya decreasing count difference. In such an installation, the digitalcomparators have an output coupled to circuit 610 to vary the drivesignals and the motor speeds accordingly.

It is noted that cam C-9 is positioned to control the hoist motor 167such that the lift platform stops when the rails 154 on the carriageassembly 170 associated with the lift platform 150 are slightly abovethe aisle rails 18 of the desired aisle level. Lift platform 150 isstopped in this position to allow the locating means 160 on the platform(FIG. 11) to accurately position the guide rails 154 with the rails 18before slightly lowering the platform 150 to seat the rails 154 to therails 18 as now described.

The hoist motor control circuit 627 generates an actuation signal whichis applied to an align control circuit 635 once the lift platform 150 ofthe mobile vertical lift 100 has stopped. Circuit 635 energizes theactuators 195 (FIGS. 11 and 12) to cause the pair of trapezoidal members180 to swing inwardly. Once they are horizontally positioned, a limitswitch L-11 (FIG. 11) is contacted and actuated. Switch L-11 iselectrically coupled to the hoist motor 167 via control circuit 627 tocause the hoist motor to lower lift platform 150 slightly as the roller188 of the locating means 160 travels within the trough 183 (FIGS. 12and 13). The trapezoidal members 180 thereby settle upon the flatsurface 181 of the guide rails 18 (FIGS. 11, 12 and 13). The tension inthe lifting cable 162 (FIG. 5) is detected by the limit switch L-12which is also coupled to the control circuit 627 and deactivates thehoist motor 167 once the rails 154 on the carriage assembly 170 havebeen seated to the guide rails 18 of the desired aisle. In this manner,therefore, the platform 150 and carriage assembly 170 thereon is easedinto accurate horizontal and vertical alignment by means of the aligningmeans which control the hoist motor to vertically align the rails, andmoves the carriage assembly 170 to the left or right on the pivot 175 tohorizontally align the rails.

In addition to the limit switches already discussed, the mobile verticallift 100 includes additional limit switches such as the switch L-13(FIGS. 5 and 21) which inactivates the hoist motor in the event that anexcessive load is present on the lift platform 150. This switch therebyprovides overload protection by preventing the actuation of the hoistmotor 167. Also electrically coupled to the hoist motor 167 is a lowertravel limit switch L-14, (FIGS. 5 and 21) and an upper limit travelswitch L-15 both of which are physically mounted to the lift 100. Leftand right end travel limit switches L-14' and L-15' (FIG. 11) arecoupled to the drive motor control circuit 613 (FIG. 21) and prevent themobile vertical lift 100 from traveling beyond the ends of rails 14 and16. An over travel limit switch L-16 mounted above switch L-15 iselectrically coupled to motor 167 and will activate the hoist motormomentarily in reverse to lower platform 150 slightly in the event thatan over travel exists due to the momentum of upward travel of theplatform 150 after the motor has been shut off by L-15, or if L-15should fail to operate. An additional protective feature is detector S-5which senses the cable tension. In the event the cable 162 breaks, thedetector S-5 provides a control signal to stop the motor. Devices on theplatform 150 sense broken cable and actuate mechanical means (not shown)which freezes the position of the lift platform 150 within the frame ofthe mobile vertical lift 100.

The store mode of operation of the system is continued after the mobilevertical lift 100 and loaded transfer vehicle 200 is aligned with thepredetermined aisle and aisle level by discharging the mobile transfervehicle 200 from the mobile vertical lift 100. During the interval inwhich the mobile vertical lift 100 is traveling from the home stationwhere it picked up the loaded transfer vehicle and arrived at thepredetermined aisle bin and location, the computer control circuit 530has provided the mobile vertical lift control and interface circuit 610with programming information for the mobile transfer vehicle. Thus, themobile transfer vehicle will receive information as to which particularstorage bin 21 it is to travel and to which side of the aisle thepalletized load 210 is to be transferred. The programming of the mobiletransfer vehicle is accomplished by means of the information transferpanel 650 which is part of the mobile transfer vehicle control circuit600 and is mounted on the mobile transfer vehicle as shown schematicallyin FIG. 19. This panel is shown in detail in FIG. 22.

The information transfer panel 650 has a left side 652 which comprisesan array of individual photoelectric detectors 654, and right side 656comprising an array of light sources such as light emitting diodes 658.The left side 652 is divided into an upper region 653 and a lower region655 corresponding to store and retrieve modes of operation,respectively. It is noted that the mobile vertical lift, and each of theinput and output stations have similar information transfer panels withthe light sources and detectors reversed so a light source on thetransfer vehicle will be aligned with a light detector on theinformation panel, the input or output station, or the mobile verticallift; and vice versa. In some embodiments, it may be desired to provideeach aisle end with an information transmitting panel 370 (two shown inFIGS. 1 and 2) so that instead of programming the mobile transfervehicle while on the lift, it is programmed after it leaves the lift andis within an aisle. In such an arrangement, each aisle end panel 370 iscoupled to the computer control to receive programming information whichis then transferred to the vehicle via panels 370. The panels have anarray of light emitting diodes and an array of photoelectric detectorswhich align with and correspond in position to the array ofphotoelectric detectors 654 and light emitting diodes 658, respectively,on the panel 650 of the mobile transfer vehicle. Thus, when the transfervehicle 200 is on the mobile vertical lift 100, on the input or outputstation or at an aisle end; the information panel 650 will be alignedwith a corresponding information transfer panel and enable the transferof information between the two panels by the optical means thereon.

The array of photoelectric detectors on the left side 652 of panel 650(FIG. 22) receive information from a mini-computer in the computercontrol circuit 530 by means of the mobile vertical lift control unit610 which has an information transfer panel 350' (FIG. 11) coupledthereto. A predetermined number of the photoelectric detectors 654 inthe upper array 653 are assigned the function of receiving informationas to the bin location to which the mobile transfer vehicle 200 is totravel once discharged from the vertical lift 100. Another one or two ofthe photoelectric detectors 654 is employed to receive information as towhether the load transferring forks 240 of the mobile transfer vehicleare to extend to the left or to the right side and if one or both forksare to be employed. Finally, one or more of the detectors 654 receivesinformation as to whether the mobile transfer vehicle is to store orretrieve to control the sequence of operation of the load transferringforks 240. By using two sections 653 and 655, the transfer vehicle canfirst store a palletized load and then retrieve another load withoutrequiring a return trip to the mobile vertical lift or aisle end for newinformation. The operation of the mobile transfer vehicle as it isdischarged from the mobile vertical lift and travels down an aisle isbest understood by referring to FIGS. 14, 14A, 19 and 23 which show thevarious sensors employed with the mobile transfer vehicle and thecontrol circuits used therewith to control the operation of the drivemechanism on the mobile transfer vehicle.

As the mobile vertical lift travels down aisle 120 to the preassingedaisle and aisle level, the array of lights on the information panelthereon are actuated to actuate the corresponding array of photoelectricdetectors 654 on the mobile transfer vehicle such that a digital countis entered into the counter 660 and a binary number corresponding to thebin into position store 660', both circuits being coupled to the panel650. The stored count and binary number corresponds to and uniquelyidentifies the desired bin location at which the load is to be stored.Each of the vertical support members 20 on one side of the aisle (FIGS.3 and 15) forming the storage rack of the storage system, have a columnlabel 11 (FIGS. 3 and 19), one of which is shown in detail in FIG. 14A.

Referring now to FIG. 14A, it is seen that each column label 11 includesa unique man readable bin number at the top area 40. The labels areprinted on non-gloss self-adhering paper which forms a label which canbe applied to a vertical support at each bin location. Just below area40 are left and right centering bars 42 and 43 respectively which areblack rectangular areas offset as seen in the figure. Dots 41 on thevarious label areas indicate the center of view of variousphotodetectors employed to read the information on the label. Thecentering bars are detected by a pair of vertically spacedphotodetectors on the transfer vehicle sensor 265 to provide controlsignals to the transfer vehicle drive motor via logic circuit 672 (FIG.23) to provide creep left or creep right speed control for accuratefinal alignment of the transfer vehicle with a desired bin as explainedbelow.

Below the centering bars on label 11 are a series of seven verticallyspaced areas 44 which are selectively blackened to provide a unique 7bit binary coded position signal to the position detector circuit 665'(FIG. 23). This provides a bin check in addition to the counting schemeas described below.

Finally, below the areas 44, each label 11 includes a reflective strip45 which is detected by a sensor on the transfer vehicle sensor panel265 to increment or decrement reversible counter 665 (FIG. 23) therebycounting the bins as the transfer vehicle travels along an access aisle.The sensor panel 265 on the transfer vehicle (FIG. 14) includes a lightsource 266 which sends a beam of light outwardly from the vehicle 200 toilluminate the entire label 11. Panel 265 includes also a plurality ofphotoelectric detectors 267 which are vertically spaced to register withthe centering bars, the code areas and the reflective tape area of label11. In this manner, therefore, accurate bin counting and binidentification information is obtained by the mobile transfer vehicle.The stored digital count programmed into the storage counter 600 and theactual representative of the position of the transfer vehicle is fed toa digital comparator 670 that provides a difference count. The output ofcomparator 670 is coupled to a logic circuit 672 which provides anenabling signal applied to the drive motor control circuit 674. Circuit674 provides an actuation signal to the transfer vehicle drive motor 275(FIG. 16) when the preset count differs from the actual position count.

The limit switch L-11 (FIGS. 11 and 21) is also coupled to the motorcontrol circuit 674 and serves to actuate the motor 275 initially todispatch the mobile transfer vehcile 200 from the mobile vertical lift100 once the locating means 160 (FIG. 11) are properly in place asindicated by the limit switch L-11. The circuitry shown in FIG. 23operates to position the mobile transfer vehicle 200 in alignment withthe desired bin by controlling the drive motor 275 in the followingmanner.

Initially, the stored count in counter 660 and the actual position countin reversible counter 665 can (for example, if the mobile transfervehicle 200 is to travel to the middle or beyond the middle of thestorage rack), be relatively high. As the transfer vehicle 200 travelsaway from the lift 100 it will, depending upon the distance it musttravel, move at high, intermediate or slow speeds. As the vehicleapproaches the desired bin, the count between circuits 660 and 665approaches coincidence. This effect is utilized to slow the speed of thetransfer vehicle 200 prior to reaching the desired bin 21 to preventovershoot in the following manner.

The digital comparator 670 will detect coincidence between the presetcount in storage counter 660 and the actual count in reversible counter665. Upon detecting one greater than coincidence of the two counts,comparator 670 develops a control signal which is applied to the logiccircuit 672 which responds to generate a second slow-down signal appliedto the motor control circuit 674 via conductor 673. Thus, when themobile transfer vehicle is one bin away from its desired destination,the drive motor 275 will be slowed to a creep speed. As the vehicleapproaches the desired bin, the digital comparator 670 will detectcoincidence between the counts in the storage counter 660 and thereversible counter 665 and produce an enabling signal which is appliedto the logic circuit 672. When the logic circuit receives this signal,it applies a stop signal to the motor control circuit 674 which thenremoves power from the drive motor 275 and the vehicle comes to a stopin approximate alignment with the storage bin.

At this time, the transfer vehicle is at rest and the position matchingcheck is automatically conducted. The top pair of photodetector sensorson panel 265 on the vehicle check stop bars 42 and 43 on label 11 to seeif exact positioning has been achieved. If not, the logic circuit 672,which is coupled to these sensors via conductor 669, generates a signalwhich is applied to the motor control circuit to actuate drive motor 275at a creep speed in a direction to correct for any slight misalignment.As exact alignment is achieved and the same luminance level is detectedby the top pair of sensors in panel 265, the drive motor is stopped.

In the event a simple counting scheme is employed without the use of acoded label for providing centering bars as well as a redundant binidentification check, locators 290 can be employed to provide accuratefinal alignment of the vehicle with respect to the storage bin. In suchan embodiment, the motor control circuit provides an enabling signalalong conductor 671 to the locator control circuit 678 which actuatesthe locator 290 (FIGS. 16 and 19) to extend the forked member 295outwardly to span one of the vertical support members 20 adjacent thedesired bin as seen in FIG. 16. The vehicle 200 may thereby be movedslightly to accurately position the transfer vehicle in relation to thebin opening.

It is noted that the logic circuit 672 can be designed such that thespeed of the drive motor 275 is continuously varied and decreased as thetransfer vehicle approaches the desired bin as indicated by thedecreasing differences between the counts in the storage and positioncounters and the reversible counters as detected by the digitalcomparators.

Once the mobile transfer vehicle is aligned with the desired storagebin, its position is checked by comparator 670' which compares theposition signal stored in register 660' with the signal detected by thephotodetectors which scan the code areas 44 of label 11. If coincidenceis detected, the storage cycle can be continued. If however, thetransfer vehicle has, for some reason, stopped at the wrong bin, thelogic circuit will detect a non-coincidence signal from comparator 670'and can either generate a corrective drive signal by resetting the countin storage counter 660 (via conductor 675) to correspond to either thelocation of the bin as indicated by the coded address stored in register660' or send the transfer vehicle to the end of the aisle to await amobile vertical lift and later reprogramming.

Once the vehicle is positioned at the correct bin, the storage cycle iscontinued by transferring the load on the vehicle into the storage bin.It is necessary to raise the forks 240 (FIGS. 14 and 16 through 18) ifnot in a raised position, extend them to position the load within thestorage bin, lower the forks, and once again retract the forks to thetransfer vehicle. This sequence is initiated by the logic circuit whichapplies a signal to the fork control circuit 680 (via conductor 679)once comparator 670' verifies the positioning of the vehicle. In systemsusing the locators 290, the sequence is initiated by the limit switchL-17 which is physically coupled adjacent the locator 290 such that oncethe locator 290 is fully extended thereby insuring the alignment of themobile transfer vehicle, the switch L-17 is actuated to provide anelectrical control signal which is applied to the fork control circuit680 (FIG. 23).

The fork control circuit also receives data from the informationtransfer panel 650 indicating whether it is to move the forks to theleft or to the right side of the aisle and whether it is a store orretrieve mode of operation. This information tells the fork controlcircuit in which direction to extend and retract the forks as well aswhether to raise or lower the forks after they have been extended as isrequired in the retrieve mode of operation discussed briefly below. Itis noted that the bins 21 are designed such that they will receive onlyone palletized load, several bins being employed for common items in thewarehouse or alternately the bins are inclined with rollers such thatthe palletized load thereon will always be toward the front of the binand the mobile transfer vehicle can push the palletized load therein. Inthe preferred embodiment, the bins were designed such that only one binwas used for each palletized load, and the mini-computer in the computercontrol circuit 530 has information as to which bins are empty and,therefore, available for storage as well as which bins have certaintypes of material therein desired to be retrieved.

As noted earlier, since the two forks can be independently operated, astorage bin could contain two half-sized pallets and one or both couldbe stored or retrieved. For purposes of explaining the fork operation,it will be assumed that the fork control circuit 680 actuates both forks240, it being understood that two such circuits could be provided toindependently control each fork. The various limit switches discussedpertain to one of the forks, it being understood that for independentoperation both forks have similar switches physically coupled thereto.It is noted here that to preserve the battery power for the transfervehicles, it is preferred to carry the loads on the vehicle in a raisedposition once the forks have been raised to lift a pallet from a bin orthe input station. In storage operation, circuit 680 first actuates theextension motors 212 (FIGS. 16 and 19) to cause the extension mechanismto extend the forks as described above in conjunction with FIGS. 16, 17and 18. The palletized load 210 carried thereon then will be positionedin the storage bin slightly above the horizontal support members 22(FIGS. 3 and 15).

Once the forks are fully extended, for example, to the left in FIGS. 3and 19, a limit switch L-19 which is physically attached to theextension mechanism is actuated and provides an electrical signal to thefork control circuit 680 which deactuates the extension motors 212 andsimultaneously actuates the raising motors 242 such that the motors willbe driven in a direction to lower the platforms 245 and forks 240thereon. When the load supported on the forks 240 is lowered into thestorage bin, a limit switch L-20, which is mechanically coupled to theplatforms 245, is actuated as the platforms reach the extreme loweredposition. The actuation of L-20 initiates the reactuation of theextension motor 212 in the reverse direction to retract the forks 240once the load rests on the storage bin support members 22 andsimultaneously causes the circuit 680 to deactuate the raising motor242. A limit switch L-22 is also coupled to the extension mechanism andis actuated thereby once the forks are in their centered position on thetransfer vehicle and provides an electrical signal to the fork controlcircuit 680 which deactivates the extension motor 212. It is noted thatthe forks also have a right side limit switch L-21 which indicates tothe fork control circuit 680 that the forks have been extended fully tothe right when a load is to be stored or retrieved in a bin located tothe right of the mobile transfer vehicle. By employing a plurality oflimit switches which are mechanically coupled to the forks and liftingplatforms and electrically coupled to circuit 680, extension and raisingmotors can be controlled to raise, extend, lower and retract the forksin the store mode of operation or extend, raise, retract and lower theforks in the retrieve mode of operation depending upon the informationreceived from the panel 650. The circuit is normally employed to extendboth forks simultaneously. In some cases, clutch 211' (FIGS. 16 and 17)is actuated such that only one fork is used. Also, each fork can haveits own control circuit and be independently operated.

In the event that an error has been made by the minicomputer or by theoperator at the control station 330 and a pallet is presently in a binin which it is desired to store another pallet or alternately during theretrieve mode of operation, the bin is empty; sensor S-6 (FIG. 19)physically mounted to the forks indicate the lack of weight on the forksor pressure tending to resist the movement of the fork into the storagebin. These sensors provide a signal to the information transfer panelsection 656 (FIG. 22) via panel 650 to convey this information to thecomputer via the mobile vertical lift 100 and festoon cable 325. Thesensors are indicated generally as S-6 by the block diagram in FIG. 23and are coupled to the information transfer panel 650 as shown. Thevehicle 200 responds to signals from S-6 to return to the mobilevertical lift 100 in the event of an inventory error. Thus, the mobiletransfer vehicle can provide diagnostic information to the computer tocorrect for any possible errors in the inventory as well as receive newinformation therefrom if one of the storage bins is empty or previouslyloaded such that the transfer vehicle can carry the load to anotherstorage bin or alternately travel to another storage bin to receive aload.

Once the load has been discharged into a storage bin and the limitswitch 22 has indicated that the forks are again centered on the mobiletransfer vehicle, the motor control circuit 674 which also receives asignal from the limit switch L-22, is again actuated to propell themobile transfer vehicle 200 back to the end of the aisle for movementonto the mobile vertical lift. The drive motor 275 is reversed and thestorage counters 660 are reset to a predetermined number correspondingto the end of the aisle by means of a reset pulse developed from thelimit switch L-22 and applied to the counter 660 via conductor 682. Itis noted that the discussion here is limited to a simple store orretrieve function by the transfer vehicle, it is understood that thetransfer vehicle could be programmed to first store a palletized load ina predetermined storage bin and once the forks are retracted onto thetransfer vehicle travel to a second storage bin to retrieve a loadbefore it again returns to the end of the aisle and is picked up by themobile vertical lift.

As the mobile transfer vehicle 200 travels toward the end of the aisleadjacent the mobile vertical lift aisle 120, the the coincidencedetected by comparator 670 causes the logic circuit 672 to reduce thespeed of the drive motor 275 to a creep speed as the transfer vehicleapproaches the aisle end. If the mobile vertical lift has during thetime the mobile transfer vehicle was in the aisle performing its loadtransferring functions, been called to pick up another transfer vehicleor otherwise been dispatched from the aisle at which the transfervehicle was discharged; the mobile transfer vehicle will automaticallycome to a stop at the end of the aisle by virtue of the coincidencedetected by comparator 670 as the count in the storage counter 660 andthe reversible counter 665 coincide. The logic circuit 672 will thentrigger the motor control circuit 674 to stop motor 275 and the transfervehicle 200. In the event the mobile vertical lift 100 is not inposition to receive the transfer vehicle 200, the vehicle will remain atthe aisle end until a mobile lift arrives and couples to the guide rails18 of the aisle thereby triggering a sensor S-8 as described below tocause the vehicle 200 to move onto the lift.

A sensor S-7 is mounted at each aisle end (FIG. 11) and detects thepresence of an awaiting mobile transfer vehicle 200. Each sensor S-7 iselectrically coupled to the computer control circuit 530 as indicated inFIG. 20 and uniquely identifies the aisle. Thus, the circuit candispatch the mobile vertical lift 100 to pick up an awaiting transfervehicle 200. If more than one vehicle is awaiting pickup, they will besequentially received by the lift 100.

In the event, however, that the mobile vertical lift is still positionedat the aisle and the tracks are in position, a sensor S-8 (FIG. 19),which is an optical detecting means mounted to the transfer vehicle,detects the aligned presence of the mobile vertical lift 100 to guiderails 18 of the aisle as indicated by a suitable light source positionedon the mobile vertical lift and actuated when the aligning means 160have locked the rails together. S-8 is electrically coupled to the logiccircuit 672 and delays the normal stop signal for a distancecorresponding to two more detected counts by the detector 265. Thus, themobile transfer vehicle will continue onward onto the mobile verticallift which has a label 11 on the vertical members 104 (FIG. 5) at eachaisle level such that the sensor 265 can be used to align the vehicle onthe lift in the same manner as it aligns with a storage bin.

Once the mobile transfer vehicle is positioned on the mobile verticallift, sensor L-1 indicates this condition to the mobile vertical liftcontrol circuit 610. The circuit 610 then applies a signal via conductor611 to the align control circuit 635 which activates actuator 195causing the members 180 of the aligning means 160 (FIG. 11) to againswing outwardly. The signal from L-1 also causes the hoist motor controlcircuit to raise platform 150 slightly which facilitates the operationof the aligning means 160. A limit switch L-23 which is physicallypositioned to be contacted by the member 180 (FIG. 11) provides anelectrical control signal to the mobile vertical lift control circuit610 indicating that the lift 100 is decoupled from the storage racks andready to be moved. Circuit 610 then actuates the hoist and drive motors167 and 130 in a manner similar to that discussed above to return themobile vertical lift to the home position as well as lowering the liftplatform 150 to the home position such that the mobile transfer vehiclecan be discharged to the input or output sides of the home station 300(FIG. 13). When the lift 100 receives control signals sending it to thehome station, the bridge control circuit 502 (FIG. 200 simultaneouslyreceives a signal from the computer control circuit 530 to actuate thebridge mechanism retracting the bridge out of the way of lift 100.

Alternatively, the mobile vertical lift can be programmed to dischargethe mobile transfer vehicle onto the guide rails 395 at the rear of thestorage bins 10 (FIG. 1) such that the transfer vehicle can bedispatched to a different facility.

The circuitry described in FIGS. 20 through 23 is also employed in theretrieve mode of operation in which a mobile transfer vehicle 200 can bepicked up at the home station 300 (FIG. 3) from the magazine storagefacility 350 such that the empty transfer vehicle is carried to apredetermined aisle and aisle level by the mobile vertical lift 100 anddischarged to travel down the aisle to a preassigned bin location, pickup a stored pallet therein and return to the home station to dischargethe transfer vehicle at the output station 340. It is noted that theoperation of the load transferring forks at the input and outputstations 320 and 240 respectively, is controlled by the associatedinformation transfer panels 370 (FIG. 1) located at these stations. Thepanels 370 interact with the panel 650 on the transfer vehicle (FIG. 22)and are electrically coupled to the computer control circuit 530 (FIG.20) to receive control information therefrom. In this manner, thepalletized loads are transferred to and from the input and outputconveyors 322 and 345 respectively by means of the transfer vehicleitself.

The stub conveyor 385 may include an information transfer panel (notshown) which interfaces with panel 650 on the transfer vehicle 200 tocause the vehicle to transfer a load thereto which will be carried bythat conveyor to another facility. It is noted that the input and outputstations 320 and 340 as well as the tracks 375 have column labels atregular intervals such that the transfer vehicles can be programmed toautomatically travel across the bridge 400 to any of these positions inthe same manner as it travels along an aisle to a storage bin in thestorage racks.

The magazine storage rack 350 may include means thereon for charging thebattery pack 222 of the transfer vehicles 200 while they are in storageawaiting use. Likewise, the transfer vehicles 200 can be removed fromthe end of the storage magazine remote from aisle 120 for servicing andrepairs. The transfer vehicles in the preferred embodiment were designedto travel at a nominal speed of 500 feet per minute. The system provideda through-put capacity of approximately 70 palletized loads per hourwhen a single mobile vertical lift and three mobile transfer vehicleswere used with a single bank of storage racks on one side of the mobilevertical lift.

Various modifications to this system as described herein can be made.For example, the mobile vertical lift can be employed at each aisle endof a plurality of milti-tiered storage racks 10 as shown in FIG. 24where a mobile vertical lift 100 is exclusively operable with an inputstation 320, and a second mobile vertical lift 100' is exclusivelyoperable with an output station 340 as shown. Each mobile vertical lift100, 100' has a home station 300, 300' respectively, communicant withits respective input or output station via the end positions of thetransfer vehicle storage area 350 located between the two stations 320,340. The storage area includes guide rails 358 for carrying the transfervehicles thereon. One of the aisles 12 can be used as a direct bypassbetween lifts 100, 100'; it being understood that each aisle 12 includeguide and support means for the transfer vehicles. The control circuitsdiscussed above can be employed with the circuitry for the additionallift 100'.

Referring now to FIG. 25, there is shown a nine aisle storage rackstructure which is constructed in the same general manner as the storageracks shown in FIGS. 1 through 3. Across the end of the access aislesextends a transverse aisle 120 which carries three independently movablemobile vertical lifts 100A, 100B and 100C. Each mobile vertical lift 100nominally services three adjacent access aisles although in certainconditions where increased activity is taking place at one end of thestorage system, the mobile vertical lifts can be controlled to servicegreater or fewer access aisles as needed.

There is provided three input/output stations 700A, 700B and 700C towhich the mobile vertical lifts transfer mobile transfer vehicles 200when the vertical lifts are at the home stations 300A, 300B and 300Cpositioned along aisle 120 as shown in the figure. Each of theinput/output stations 700A through 700C includes guide rails constructedsimilar to the rail arrangement shown in FIGS. 1 through 3 for theinput/output stations described therein and each of the home stations300A through 300C includes a retractable bridge similar to that alsoillustrated in FIG. 3. The input/output stations are positioned acrossthe transverse aisles from the storage racks. Each of the input/outputstations is positioned between an input conveyor 710 and an outputconveyor 720 such that loads can be transferred between a mobiletransfer vehicle at the station and the conveyors.

In addition to providing a station whereupon palletized loads can betransferred from the mobile transfer vehicles to an output conveyor orreceived by the mobile transfer vehicle from an input conveyor; each ofthe input/output stations 700A through 700C have guide rails whichextend to a storage magazine area 730 such that mobile transfer vehiclesnot in use can be positioned in the storage magazine out of the way ofthe operational components of the system. In the figure, two vehiclestorage locations are indicated in dashed lines for the magazine 730associated with station 700B.

A central input conveyor 715 communicates with each of the inputconveyors 710 by means of a sorting conveyor 712 which sorts labeledarticles to the input conveyor associated with the input/output stationwhich is serviced by the mobile vertical lift covering the storage areafor that article. Thus, the sorting conveyor 712 includes conventionalsorting means for discharging palletized articles from the conveyor ontothe appropriate input conveyor 710. An accumulation conveyor 722 iscommunicant with each of the output conveyors 720 to gather articlesfrom the conveyors and transport them to the main output conveyor 725which interfaces the warehousing system with, for example, a shippingdock, manufacturing facilities or other locations.

The controls and sensors for the mobile transfer vehicles as well as themobile vertical lifts are substantially the same as for the embodimentdescribed in detail above. Thus, the mobile transfer vehicle iscontrolled by sensing a plurality of column labels located on thestorage bins as well as the input/output station and storage magazineareas. The mobile vertical lifts are controlled by sensing aisle andaisle level identification means positioned at the ends of the aisles.Each of the mobile vertical lifts will include its own control circuitsand a computer control will control the operation of the three mobilevertical lifts along the transverse aisle 120 such that they can eachservice three aisles independently or, as noted above, in the event thatone or more aisles are heavily used, one or more mobile vertical liftscan be selectively controlled to service these aisles withoutinterferring with each other.

With the system of FIG. 24, a relatively large storage rack facilitywith long access aisles can be even more efficiently operated byemploying a pair of mobile vertical lifts with transfer vehicles 200 atopposite ends of the system. Another embodiment of the present inventionis shown in FIG. 25 and is also useful to increase the through-put ofthe warehousing system when a single bank of storage racks with verylong access aisles are employed.

Thus, it is seen that the mobile vertical lift together with the mobiletransfer vehicle system can provide fully automatic or semi-automaticoperation with an improved efficiency of material handling between inputand output stations in a warehouse or between facilities such as storageand assembly facilities. Various modifications to this system willbecome apparent to those skilled in the art and will come within thescope of the invention as defined in the appended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A materials handlingsystem comprising: a multi-level storage rack having a plurality ofstorage bins arranged in arrays on each level along a plurality ofaccess aisles, pairs of horizontally spaced rails extending along andcoupled to facing ends of storage bins on opposite sides of each aisleat each storage bin level, said rails extending adjacent the storagebins, a mobile vertical lift movable across the ends of the accessaisles and alignable with a desired aisle, said mobile vertical liftincluding a lifting platform movable in a vertical direction to reachany desired storage bin level; a plurality of self-powered mobiletransfer vehicles each including drive and support wheels andindependently movable along an access aisle at a selected single storagebin level, each of said mobile transfer vehicles including means thereonfor transferring articles between said mobile transfer vehicle and astorage bin at the same level as said mobile transfer vehicle, saidmobile vertical lift being adapted to transport said mobile transfervehicle thereon to a desired aisle and storage bin level and dispatchsaid mobile transfer vehicle therefrom, wherein each of said rails ofsaid pairs of rails includes end stops pivotally mounted to obstruct themovement of said mobile transfer vehicle beyond said end stops when saidend stops are in a first position, and wherein said mobile vertical liftincludes camming means engaging said end stops of a selected aisle andaisle level for moving said end stops to a second position permitting amobile transfer vehicle to be transferred between said mobile verticallift and guide rails of a selected aisle and aisle level; and whereinsaid lifting platform of said mobile vertical lift includes a pair ofhorizontally spaced guide rails for supporting said mobile transfervehicle thereon and wherein said camming means includes bridge means forcoupling said guide rails on said lifting platform to said guide railsof said selected aisle and aisle level.
 2. A materials handling systemcomprising: a multi-level storage rack having a plurality of storagebins arranged in arrays on each level along a plurality of access aislesand on opposite sides of a respective access aisle, vertically spacedrails extending along and coupled to facing ends of storage bins onopposite sides of each aisle and at each storage bin level laterallyadjacent said access aisles, said rails extending adjacent the storagebins, a mobile vertical lift movable horizontally across the ends of theaccess aisles and alignable with a desired aisle, said mobile verticallift including a lifting platform movable in a vertical direction toreach any desired storage bin level; a plurality of self-powered mobiletransfer vehicles each independently movable along an access aisle at aselected single storage bin level on said rails associated with saidselected single bin level, wherein said mobile transfer vehicle includesdrive and support wheels supported by said rails when said mobiletransfer vehicle is within an aisle, each of said mobile transfervehicles including selectively programmable control means and meansthereon for transferring articles between said mobile transfer vehicleand a storage bin at the same level as said mobile transfer vehicle,said mobile vertical lift being adapted to transport said mobiletransfer vehicle thereon to a desired aisle and storage bin level anddispatch said mobile transfer vehicle therefrom, means on said mobilevertical lift to selectively program said control means on said transfervehicles, wherein said mobile vertical lift includes means forsupporting said mobile transfer vehicle thereon, alignment means mountedon said rails adjacent the ends thereof; said mobile vertical liftincluding bridge means thereon movable about a vertical axis andoperative to engage said means to urge said mobile vertical lift intoalignment with said rails and for coupling said support means of saidlifting platform to said rails of said selected aisle and aisle level topermit a mobile transfer vehicle to be transferred between said mobilevertical lift and the support means of a selected aisle and aisle level.3. The system as defined in claim 2 wherein each of said rails of saidpairs of rails includes end stops pivotally mounted to obstruct themovement of said mobile transfer vehicle beyond said end stops when saidend stops are in a first position, and wherein said bridge meansincludes a portion engaging said end stops of a selected aisle and aislelevel for moving said end stops to a second position permitting a mobiletransfer vehicle to be transferred between said mobile vertical lift andguide rails of a selected aisle and aisle level.
 4. The system asdefined in claim 3 wherein said support means of said mobile verticallift includes a pair of horizontally spaced guide rails for supportingsaid mobile transfer vehicle thereon.
 5. The system as defined in claim2 and further including an input station and an output station eachassociated with said system and a home station for said mobile verticallift, said mobile vertical lift movable to align with said home stationsuch that a mobile transfer vehicle can be discharged from said mobilevertical lift to said input or output stations.
 6. The system as definedin claim 2 and further including computer means coupled to said controlmeans of said mobile vertical lift for providing programming informationthereto.
 7. The system as defined in claim 2 wherein each of saidcontrol means of said mobile transfer vehicle and said mobile verticallift include transmitting and receiving means which align fortransferring information therebetween when said mobile transfer vehicleis positioned on said mobile vertical lift.
 8. The system as defined inclaim 7 wherein said transmitting and receiving means comprises anoptical interface panel including an array of light transmitting meansand an array of light detecting means.
 9. The system as defined in claim2 wherein said lifting platform includes a carriage assembly includingguide rails thereon adapted to receive a mobile transfer vehicle, saidcarriage assembly being movable on said platform in relation to saidguide rails to permit accurate alignment of said rails to guide railswithin an aisle.
 10. The warehousing system as defined in claim 9wherein said bridge means on said mobile vertical lift comprisessegments of guide rails pivotally coupled to ends of said guide rails onsaid carriage assembly and operable to move into aligned and lockedengagement with said alignment means adjacent ends of said guide railsin said aisles.
 11. The warehousing system as defined in claim 2 whereineach of said mobile transfer vehicles include locating means foraccurately positioning said mobile transfer vehicle adjacent apredetermined storage location.
 12. The warehousing system as defined inclaim 11 wherein said locating means comprises a retractable andextensible fork having a pair of tines adapted to be selectivelyextended such that said tines span a vertical support member forming aboundary of a storage location thereby fixing the position of saidmobile transfer vehicle therewith.